I need a grille for doing mainly chicken, there is an inkling to buy a gas grille but I heard charcoal grilles are better for flavour, I like the convenience of gas, but flavour is compelling, is this true?

This is very subjective but I think charcoal grilled food is better. Although I have found that larger quantities is easier to make on a gas grille because it is easier to keep the temperature on the same level for a longer time.

Because of the differences others have mentioned, I actually own both. I prefer the taste of charcoal but just don't have the time or energy for charcoal sometimes.

My main grill is a gas grill, which is very large, convenient and easy to use. I can have grilled chicken go from fridge to plate in about 15 minutes, including prep, without having to do almost any work at all. I also have a smoker box for when I want to use wood chips in the gas grill. I also sometimes cook on wood planks in my gas grill, such as salmon on cedar. As johnny mentioned, when I have a large amount of guests, I find it much easier to work with my gas grill.

Then, for when I have the time or energy, such as when I have a couple guests over for a nice steak on a Saturday, I pull out my small, cheap charcoal grill and chimney starter (which heats the coals faster and more evenly).

I'm a big charcoal advocate. You can get higher temperatures from charcoal, and a good grill (read: Weber kettle) offers a great deal of flexibility. It's easier to deal with flare-ups, and once you attain a good skill level you can have more consistent temperatures across your cooking surface. Plus, it tastes better.

Once I started using lump charcoal and a chimney starter, I have been able to get up and running a lot quicker. Usually I'll start a chimney full of coals, then do my prep work on the food. Within 10-15 minutes, the coals are ready for cooking (using Kingsford briquettes, it's more like 20-25).

However, I find the biggest benefit to be the use of indirect heat. You can use a gasser to cook food indirectly, but it's just not designed to do cooks that way, making for a very inefficient cooking method. I've used my big gas grill in the past, but it uses a lot of propane, and a lot of heat escapes from under the hood. The kettle, on the other hand, is designed to convect heat. Particularly for roasting/barbecuing at somewhat higher temps (350F+), charcoal is the way to go.

Overall, I recommend having both. Spend 100 less dollars on whatever gas grill you want to buy, and complement it with a Weber One Touch Silver (80 bucks for the 22") or something comparable.